1. Field of the Invention
This invention pertains to the demetallization of petroleum crude oils. More particularly, the invention relates to an improved method of demetallizing Venezuelan petroleum crude oils in the presence of demetallization catalyst or contact solids and hydrogen wherein the demetallization catalyst life is extended thereby substantially reducing catalyst replacement costs.
2. Description of the Prior Art
Federal environmental pollution standards are becoming increasingly stringent with respect to the permissible amount of sulfur emissions. Due to the increasing demands for energy coupled with the need for low sulfur content fuel oil, energy needs are being met through the upgrading of high sulfur petroleum residuum. To this end, many methods are known for desulfurizing these high sulfur containing residuums. However, one of the greatest difficulties in desulfurizing such feedstocks is due to metal containing contaminants, for example, vanadium and nickel, which rapidly poison desulfurization catalysts by blocking active sites, thereby rendering sulfur removal possesses economically unattractive. In order to obviate such problems many prior art methods are disclosed for the removal of vanadium and nickel from petroleum residuums in the presence of demetallization catalysts or contact solids and hydrogen.
Examples of such prior art methods can be found in U.S. Pat. Nos. 2,764,525 and 2,730,487 which disclose treating petroleum fractions with iron oxide on alumina and Titania on alumina respectively to remove metals. U.S. Pat. No. 2,776,183 discloses a demetallization process utilizing Fuller's Earth, while U.S. Pat. No. 2,769,758 discloses bauxite as the demetallization material.
Another prior art method is disclosed in U.S. Pat. No. 3,964,995 which is directed to a hydrodesulfurization process in two stages wherein the first stage is a demetallization step and the demetallization catalyst is disclosed as being alumina promoted with Fe.sub.2 O.sub.3 TiO.sub.2 and/or S.sub.i O.sub.2. U.S. Pat. No. 3,985,643 discloses demetallization utilizing spent hydrodesulfurization catalyst as the demetallizing agent. Many other contact solids with demetallization activity are known in the art.
While the prior art methods disclose generally many or various methods for demetallization of petroleum feedstocks to enhance and improve the efficiency of hydrodesulfurization steps, the prior art has failed to recognize the need for extending the life of the various demetallization catalysts.
Accordingly, it is an object of this invention to provide a method for the demetallization of Venezuelan petroleum residuums in which the catalyst life is optimized.
Other and additional objectives will become obvious to those skilled in the art following a consideration of the specification herein including the drawings and the claims.